Over at Slate, June Thomas discusses how to reach the magical 50,000 word minimum for NaNo success. She cites Chris Baty, the founder of NaNoWriMo, who gives the following techniques for padding the word count.
His strategies include giving a character a stutter (to expand “the girth of their dialogue”), temporary deafness(“necessitating that everything said to him or her be repeated”), and a fondness for quotation(“Give your protagonist a copy of Beowulf and an annoying habit of reading poetry out loud on their long commute to work”).
In addition, Thomas adds a few of her own.
I have some additional suggestions: amnesia (if one or more characters forgets everything that has happened in the narrative thus far, it’s only polite to remind them—at length), flashbacks (either to events before the action of the novel began or just a couple of chapters back), recollections (of a character’s earliest childhood memories or just about anything else apropos of nothing), lists (you don’t have to stick to a character’s favorite books, music, movies; why not list every friend they ever had?), and recipes (if someone is preparing a meal, don’t stint on the details—how hot should that oven be?).
I’ve got a few too: meta-fiction (after each sentence, write a paragraph explained what you are trying to accomplish and/or include commentary on how you felt, as a novelist, writing the aforementioned sentence), spot the change (copy and paste each chapter, so there are two chapter ones, two chapter twos, etc, but make a few nominal changes and challenge the reader to spot the difference), language switch (have your main character learn another language and then include a translation (using google translator) of everything you’ve written).